monkeybusinessimages/Thinkstock(NEW YORK) -- Tennessee may be the “Volunteer State,” but a new federal survey finds Americans in all 50 states are volunteering to help their communities.

According to a new survey by the Corporation for National and Community Service and the National Conference on Citizenship, one in four adults volunteered through an organization in 2012.

According to government researchers, 64.5 million Americans volunteered nearly 7.9 billion hours last year.

The estimated value of the volunteer service is nearly $175 billion, according to an estimate of the average value of a volunteer hour.

Highlights of the annual Volunteering and Civic Life in America Survey:

Older Americans, those ages 65 and older, donated nearly twice as many hours per volunteer than the population as a whole, with a median of 90 volunteer hours in 2012 compared to 50 hours for the general population.

The volunteer rate of Generation X has trended upward over the past 11 years, increasing nearly 5.5 percentage points, and Generation X has the highest volunteer rate of any age group.

Volunteering has trended upward among teenagers over the past six years, up nearly three percentage points since 2007.

Working mothers continue to volunteer at a significantly higher rate than the population as a whole and people who do not live with children under 18, 38.5 percent compared to 26.5 percent and 23.8 percent, respectively.

The volunteer rate of parents with children under age 18 was 33.5 percent compared to the population as a whole, which was 26.5 percent.

Volunteers are almost twice as likely to donate to charity as non-volunteers.

"Volunteering is a core American value. Americans who volunteer enrich our communities and keep our nation strong," said Wendy Spencer, CEO of CNCS.

The data for the study was collected through the government’s Current Population Survey of about 60,000 households -- approximately 100,000 adults -- conducted by the U.S. Census Bureau on behalf of the Bureau of Labor Statistics.